FIELD OF THE INVENTION
The present invention relates generally to sorting apparatuses and, more specifically, to sorting apparatuses for sorting mail and other articles. Still more specifically, the present invention relates to a dual-level sorting apparatus which includes a conveying device having an upper section and a lower section, the upper and lower sections being connected so that mailpieces or articles can be circulated from the upper section to the lower section for sorting.
The machine-readable postcodes which should be specified on items of mail, such as letters, postcards, packets and the like, as an identification for a location, a postal district, a PO box or a major recipient, permit rapid, mechanical distribution of mail. In this arrangement, sorting of the incoming items of mail takes place with the aid of controllable conveyable-article carriers which are each loaded, manually or mechanically, with an item of mail in special input locations and then discharge said item of mail to a sorting container, or a corresponding sorting compartment, assigned to the respective postcode. Since, for space-saving reasons, it is desired for both the input locations and the sorting containers or sorting compartments to be arranged in various planes, the conveyable-item carriers circulating on conveying devices must, if appropriate, also be capable of spanning various levels. After transfer of the item of mail to the assigned sorting container or the assigned sorting compartment, the empty conveyable-article carrier can once again be loaded with an item of mail when it passes an input location.
U.S. Pat. No. 3,300,026 discloses a sorting apparatus for mail which has pairs of conveyable-article carriers which circulate on a conveying device and are intended for receiving, for transporting and for discharging mail, in a controllable manner. The conveying device comprises two chains which circulate endlessly at a distance from one another and that are guided in a meandering fashion over corresponding rollers and, on a plurality of planes located one above the other. The chains guide the conveyable-article carriers past in each case one row with sorting containers. The meandering progression of the conveying device in a plurality of planes results in a relatively large overall height of the sorting apparatus, with correspondingly poor accessibility to the sorting containers arranged in the top planes.
WO 95/02468 discloses a sorting apparatus, in particular for mail, which has a plurality of conveyable-article carriers which circulate on a conveying device and are intended for receiving, for transporting and for discharging, in a controllable manor, the conveyable articles to assigned sorting containers. The conveyable-article carriers are fastened on circulating transporting carriages of the conveying device, it being the case that the transporting carriages, which are driven by an endlessly circulating transporting cable, are guided, by way of rollers, on two profiles which are aligned at a vertical distance from one another and extend in the transporting direction. The transporting carriages circulate, via a vertical deflection, in two planes, with the result that, in each plane, they can be guided along in each case two parallel rows with sorting containers.
In the case of the conveying device of the sorting apparatus disclosed by WO 95/02468, the conveyable-article carriers which are loaded with conveyable articles, for example, in a rear loading zone of the bottom plane, are deflected forwards on the same level and then transported past the sorting containers arranged in a row on the front side of the bottom plane. In the region of the vertical deflection, the conveyable-article carriers are then guided obliquely upwards into the top plane and, there, are transported past the sorting containers arranged in a row on the rear side. In the region of the end side, the sorting containers are then deflected forwards on the same level and then transported past the sorting containers arranged in a row on the front side. In the region of the vertical deflection, the conveyable-article carriers are then guided obliquely downwards into the bottom plane and, there, are transported past the sorting containers arranged in a row on the rear side. In the region of the vertical deflection, the two profiles for guiding the transporting carriages and the transporting cable run, in one case, obliquely from bottom to top and, in another case, obliquely from top and to bottom in the opposite direction. Guidance of the transporting cable over two appropriately sized cable wheels arranged in the region of the vertical deflection would result in a greater overall length of the sorting apparatus. Guidance of the transporting cable over a plurality of deflection rollers arranged in the region of the vertical deflection may avoid this increase in overall length. On the other hand, the service life of the transporting cable is influenced to a great extent by the flexing of the cable which takes place as the cable runs over the deflection rollers. Moreover, aggravating running noise is produced when the transporting cable in guided over a plurality of deflection rollers.